"Nignog 3days ago
Don't use it when you have no cards in your deck because you'll just deck out. For whatever reason it doesn't let you use it anymore if you have zero cards"
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In that case, the reason why you can't use it is because it can't complete the "draw 1 card" effect. but why the hell would you wait until you've got no cards before you decide to use it? that's just dumb.